In recent years, an all-solid battery where the electrolytic solution is replaced with a solid electrolyte is attracting attention. Compared with a secondary battery using an electrolytic solution, the all-solid battery using no electrolytic solution does not cause decomposition, etc., of the electrolytic solution attributable to overcharge and moreover, has high cycle durability and high energy density.
In such an all-solid battery, a positive electrode collector layer, a positive electrode active material layer, a solid electrolyte layer, a negative electrode active material layer, and a negative electrode collector layer are generally stacked in this order, and the manufacture of an all-solid battery generally includes pressing these layers as a whole for the purpose of improving the contact at a solid-solid interface to enhance the performance of the all-solid battery.
However, it is concerned that in such an all-solid battery, the positive electrode active material layer and the negative electrode active material layer may collapse due to deformation resulting from repeated charge/discharge cycles, vibration during use, etc., and thereby coming into contact with each other to cause a short circuit of the battery. As regards this issue, a technique of suppressing a short circuit of an all-solid battery by creating a difference between the area of the positive electrode active material layer and the area of the negative electrode active material layer is known. Please note that the size of a solid electrolyte layer is generally equal to or greater than the size of an active material layer having a large area.
There is a possibility that, when an all-solid battery having the above-described configuration is produced, a small-area active material layer bites into the above solid electrode layer by applying pressure to these layers as a whole, and thereby coming into contact with a large area active material layer to cause a short circuit of the battery.
The conventional manufacturing method of an all-solid battery is described by referring to FIG. 4. FIG. 4 is a view illustrating how a laminate 1 having stacked therein a positive electrode active material layer 2 of small area, a solid electrolyte layer 3 of large area, and a negative electrode active material layer 4 of large area is short-circuited when a pressure is applied to the laminate 1 in the manufacturing process of a conventional all-solid battery.
When a high pressure is applied to the laminate 1 so as to improve the contact between layers and/or in each layer and thereby enhance the performance of the all-solid battery (FIG. 4(a)), the positive electrode active material layer 2 of small area bites into the solid electrolyte layer 3 of large area (FIG. 4(b)), and at the same time, is put into contact with the negative electrode active material layer 4 of large area to cause a short circuit. Accordingly, studies have been made for a manufacturing method of an all-solid battery capable of suppressing such a short circuit.
The manufacturing method of an all-solid battery of Patent Document 1 includes applying pressure to (first pressing) a negative electrode laminate having a negative electrode active material layer and a first solid electrolyte layer and cutting the end part of the negative electrode laminate; applying pressure to (second pressing) a positive electrode laminate having a positive electrode active material layer and a second solid electrolyte layer and cutting the end part of the positive electrode laminate; obtaining a laminate for battery by stacking the negative electrode laminate and the positive electrode laminate such that the first solid electrolyte layer side and the second solid electrolyte layer side come into contact; and heat-pressing (third pressing) the laminate for battery. The manufacturing method of an all-solid battery of Patent Document 1 discloses a technique of changing the pressing pressure among respective steps, and the pressing pressure in each step is specifically as follows:                the pressing pressure in the first pressing step (i) is 500 MPa or more;        the pressing pressure in the second pressing step (ii) is 500 MPa or more; and        the pressing pressure in the third pressing step (iii) is 100 MPa or more.        
That is, in the manufacturing method of an all-solid battery of Patent Document 1, the pressing pressure in the third pressing step (iii) is set to be smaller than the pressing pressure in the first pressing step (i) and the pressing pressure in the second pressing step (ii), and thereby preventing that one active material layer bites into another active material layer.
The manufacturing method of an all-solid battery of Patent Document 2 includes pressing a positive electrode layer and a first crystal electrolyte layer to obtain a positive electrode laminate; applying pressure to a negative electrode layer and a second crystal electrolyte layer to obtain a negative electrode laminate; and applying pressure to the positive electrode laminate and the negative electrode laminate in the state of a glass electrolyte layer being sandwiched therebetween. Patent Document 2 discloses a technique of enhancing the interlayer adherence between the positive electrode laminate and the negative electrode laminate by applying pressure to the laminates in the state of a glass electrolyte layer being sandwiched therebetween.